Concorde Alpha Foxtrot ‘D’ Check

 

This is an account of a ‘D’ Check or major overhaul which was carried out on the British Airways Concorde G-BOAF between October 1992 & June 1993

This was the longest and most comprehensive check ever carried out on a Concorde, Alpha Foxtrot spent six months in the TBB’s maintenance dock. The extended check not only included the routine major maintenance, but also included additional work which would benefit the entire Concorde fleet and provide additional data for the future of supersonic travel.

 

Consultations were carried out in conjunction with British Aerospace (Now BAe systems) and Aerospatiale (Now EADS), to facilitate fitting 31 strain gauges to the main stress points on the left wing and the left-hand side of the fuselage. Since airframe testing by Concorde’s manufacturers had ceased in the middle 1980’s. These gauges would be used to monitor loads in the airframe during 12 supersonic services – providing additional data on airframe life. Alpha Foxtrot would be the only aircraft to carry such equipment and it would be removed after these flights.

 

The Production Controller Mike Higgins began initials studies into the check list during October 1992, planning out a life extension modifications with the first installation of a Traffic Collision Avoidance System (TCAS) on a Concorde.Preliminary checks began on G-BOAF on December 21st 1992, prior to a total shut-down of its electrical and hydraulic systems. System integrity checks, covering flying control functions and hydraulic leaks were carried out along with detailed boroscope checks of each engine. At this point, Production Controller Ron Rogerson joined Mike to ensure work was fully controlled over both early and late shifts.

BA Engineering, London Heathrow

Concorde G-BOAF stipped of her paint in 1993

Part of the fleet’s life extension programme includes strengthen to the fuselage “crown area” – a 20 ft section of roof, spanning from the cabin window to window between the wings. The dorsal fin and elevons were removed for inspection and rework.

 

 

Following this thorough examination, Alpha Foxtrot was towed off to TBK’s Paint Bay to be stripped of its glossy coating. Thus, on January 4th 1993, in virginal grey aluminium, the naked Concorde arrived for an extensive re-work in TBB’s purpose-built dock.

 

In essence, this was a strip-out and re-build with additional comprehensive mod programme. Once it arrived in the dock the aircraft was jacked into place before the strip out in earnest. Pretty much well everything came out – overhead bins, wardrobes, galleys, toilets and most of the floor. Even the cabin wall insulation blankets were removed, leaving a long metal shell.

Concorde G-BOAF in the TBB, 1993

Further work included the installation of restrictors to reduce pressure peaks in the powered flying unit selector valves, and a series of modification to reduce stress concentrations. Twelve strain gauges were attached to selected points in the left wing and 18 at the floor level on the left of the fuselage, with one in the trim-tank. These were calibrated prior to a pre-service test flight.

Additionally, following a request from Boeing, four windows were replaced on the right side of the fuselage with metal blanks containing sensitive microphones. These monitored noise produced by the aircraft’s 2boundary layer” – the thin membrane of slower moving air that forms between the aircrafts skin and surrounding air – during supersonic flight. Such data will aid research into a possible Concorde successor.Four windows on the right were replaced with metal blanks containing sensitive microphones

Four windows on the right were replaced with metal blanks containing sensitive microphones

On the wings, a series of strengthening mods encompassed both engine bays where small areas of lower wing-skins were shot-peened and thrust balance attachment mounts inspected and re-worked. After removal of the engine bay doors, air intakes, primary and secondary nozzles, thrust-reverser buckets and heat shields, each bay and all-four intakes were completely rewired and every hydraulic pipe removed and renewed.

Mechanical Technicians check hydraulic piping on the left engine bay, while the right enging bay is has a re-wire

Once the work on the engine bays was completed, a progreeive re-build began, starting with new cabin insulation blankets in the cabin and replacement of engines on the wings.

 

By May 6th 1993, the aircraft was ready for its first engine run to test the rebuilt systems, this was remarkably successful. Each of the engines was tested on a series of throttle settings up to full power and there were very few defects. Given the complexity of the work carried out, it was a very satisfying result.

Concorde Tecnician Phil Rozier changes a corroded floor rail while Andy Cameron and apprentice checks wriing looms

Four days later, all access panels being refitted prior to a full re-paint, and by May 15th G-BOAF, Alpha Foxtrot was ready to face the world again, she was clad once more in gleaming red, white and blue livery. But before its public debut, the aircraft returned to the TBB to be fitted with-out with the new Concorde interior, featuring new seats, larger overhead bins, new galleys, improved toilets, a new in-flight entertainment system and new passenger and cabin lighting.

Fitting the cable for the Traffic Collision Avoidance System (TCAS)

Other D Check images - Various airframes

Great shot of the center fire wall with both engines removed

Looks like the construction of a new airframe but this shows the depth of detail on a D check

Completely stripped interior

Completely stripped Cockpit (F-BVFF)